The present invention relates generally to a flow regulation apparatus, and more particularly, to a one-way check valve which will open and close at very low differential pressures in order to prevent flow in a first direction and to allow flow in a second direction.
Automotive fuel systems typically incorporate a one-way check valve on the end of a fuel return tube within the vehicle gas tank. In a typical automotive fuel system, fuel is pumped through a supply tube to a fuel chamber at the engine in quantities in excess of that required by the engine. The excess fuel is returned to the fuel tank by way of the fuel return line and the one-way valve at the fuel tank end of the return line insures that if suction should be applied to the return line from the engine, or if the line should be damaged in the event of an accident, fuel will be prevented from flowing to the engine via the return line.
Several different check valves have been used to prevent back flow through the return line, such as a duckbill valve attached to the end of the tube. While this valve effectively controls flow of fuel through the tube, under certain conditions it may produce an undesirable noise as the fuel is returned to the fuel tank.
In another prior art valve, a plastic disk is retained within a cage attached to the end of the return tube and the disk moves toward the end of the tube to seal off the end of the tube when a negative pressure is applied to the tube. However, such a valve structure does not insure that a complete seal will be provided at the end of the tube and may not respond quickly to prevent back flow under all operating conditions.
In addition, the end of the fuel return tube may be out of round or have machining marks which interfere with sealing of the valve to the tube in certain prior art valves which are formed with body portions made of plastic materials.
Accordingly, there is a need for a one-way check valve which may be easily attached to the end of a fuel return tube and which will permit quiet forward flow of fluid through the tube. Further, there is a need for such a valve in which a small reverse flow pressure will cause the valve to close to substantially prevent all fluid flow through the return tube in a reverse direction.